Good ones to look out for offer more than just hosting, with extras like Php functionality as well as at least one MySql database, per account.
My favourites are:
- http://www.000webhost.com/ - I haven't been using it for long, but so far so good. One of my test sites, Zambezi Safari is hosted with them.
- http://www.awardspace.com/ - This is another very popular free webhost. I have often used them in the past and indeed have upgraded on of my free acounts to a paid for version.